.modal_box{
  position: fixed;
  width: 100%;
  height: 100%;
  top: 0;
  left: 0;
}
.mask{
  width: 100%;
  height: 100%;
  position: absolute;
  background: rgba(0,0,0,0.5);
}
.content{
  width: 600px;
  height: auto;
  position: relative;
  margin: auto;
  top:50px;
  background: #fff;
}